diff --git a/webapp/frontend/src/app/shared/device-hours.pipe.spec.ts b/webapp/frontend/src/app/shared/device-hours.pipe.spec.ts
index cd9f1bc..86b3aa6 100644
--- a/webapp/frontend/src/app/shared/device-hours.pipe.spec.ts
+++ b/webapp/frontend/src/app/shared/device-hours.pipe.spec.ts
@@ -1,9 +1,54 @@
-import { DeviceHoursPipe } from './device-hours.pipe';
+import { DeviceHoursPipe } from "./device-hours.pipe";
 
-
-describe('DeviceHoursPipe', () => {
-  it('create an instance', () => {
+describe("DeviceHoursPipe", () => {
+  it("create an instance", () => {
     const pipe = new DeviceHoursPipe();
     expect(pipe).toBeTruthy();
   });
+
+  describe("#transform", () => {
+    const testCases = [
+      {
+        input: 12345,
+        configuration: "device_hours",
+        result: "12345 hours",
+      },
+      {
+        input: 15273,
+        configuration: "humanize",
+        result: "1 year, 8 months, 3 weeks, 6 days, 15 hours",
+      },
+      {
+        input: 48,
+        configuration: null,
+        result: "2 days",
+      },
+      {
+        input: 168,
+        configuration: "scrutiny",
+        result: "1 week",
+      },
+      {
+        input: null,
+        configuration: "device_hours",
+        result: "null hours",
+      },
+      {
+        input: null,
+        configuration: "humanize",
+        result: "0 seconds",
+      },
+    ];
+
+    testCases.forEach((test, index) => {
+      it(`should format input ${test.input} with configuration '${
+        test.configuration
+      }' (testcase: ${index + 1})`, () => {
+        // test
+        const pipe = new DeviceHoursPipe();
+        const formatted = pipe.transform(test.input, test.configuration);
+        expect(formatted).toEqual(test.result);
+      });
+    });
+  });
 });